Here is the US Custom Harvesters website.
http://www.uschi.com/index.php They have a link on their main page about Classified Ads. There are some crews, needing help. That might help. You can also contact USCHI about finding a crew. I know that there are many South Africans, and Austrailians that come over to go on harvest, and USCHI helps them out finding work.
By the way, if you get a chance to look at their Hall Of Fame page, look up Dishman Harvesting. Those are friends of mine. I used to work for them, and I still do when they are home.
If you do find a harvest crew, have fun, get ready for some
long hours. :P Best of luck.